The present technology relates to a three-dimensional (3D) non-volatile memory device.
Recently, ultra high density storage devices have been proposed using a 3D stacked memory structure sometimes referred to as a Bit Cost Scalable (BiCS) architecture. For example, a 3D NAND stacked memory device can be formed from a stack of alternating conductive and dielectric layers. A memory hole is formed in the stack, and the hole is filled with appropriate materials to form a NAND string. A straight NAND string extends in one memory hole, while a pipe- or U-shaped NAND string (P-BiCS) includes a pair of vertical columns of memory cells which extend in two memory holes and which are joined by a bottom back gate. Control gates of the memory cells and select gate transistors are provided by the conductive layers. However, various challenges are presented in fabricating and operating such memory devices.